This invention relates to a nose mask for administering one or more gases such as oxygen to a human being.
As of 1978, about three million Americans were diagonosed as having chronic obstructive pulmonary disease (COPD). The term "COPD" is generally applied to chronic respiratory disease processes characterized by the persistent obstruction of bronchial air flow. Typical COPD patients are those suffering from conditions such as bronchitis, cystic fibrosis, asthma or emphysema. The condition of a great number of COPD patients can be improved by supplying them with a source of pure oxygen gas or a mixture of oxygen and other inert gases such that the concentration of oxygen in the mixture is greater than that amount found in air (about 21 percent by volume). Depending upon the severity of their condition, COPD patients may require administration of additional oxygen (oxygen therapy) for a period of from a few hours a day up to twenty-four hours per day for a period of time which may extend for weeks to years. In view of the potential for long-term usage, the device employed to deliver oxygen to the patient should be comfortable, efficient, simple in design, disposable or easily cleaned and sterilized, economical in terms of oxygen usage and should permit the wearer to breathe, eat and converse in as normal a fashion as possible.
The same factors are applicable to an oxygen delivery device used in a hospital for any patient requiring the administration of additional oxygen. A simple, comfortable device which places a minimum amount of restrictions on the patient's freedom to breathe, eat and talk is more likely to be worn by the patient. These factors become especially important when the device is used by a patient in his own home since hospital-type supervision and assistance is generally not available either (a) to require such a patient to wear an uncomfortable mask for the amount of time required by his condition or (b) to assist him in the event that a malfunction occurs in a more complicated delivery device such as one having a rebreather bag attached.
Various approaches to provide a device for administering additional oxygen to a patient have been taken in the past. Face masks which cover the nose and mouth both effectively and economically administer oxygen, but have the disadvantages of being hot and confining, interfere with eating and speaking and are said to be impractical for long-term oxygen therapy.
Nasal cannulas such as those described in U.S. Pat. Nos. 2,499,650 (Kaslow--patented Mar. 7, 1950) and 2,868,199 (Hudson--patented Jan. 13, 1959) have been used to avoid the confinement inherent in face masks covering the mouth. The cannulas are simply a hollow tube running directly beneath the wearer's nose which contain openings or prongs which direct the gas directly into the wearer's nostrils. The cannula also has the advantages of being comfortable, inexpensive and a means for providing a continuous source of gas, but has the disadvantages of (a) tending to dry out the mucous membranes of the wearer's nose, especially when worn for an extended period of time, (b) not being useful when the patient has complete nasal obstruction, and (c) being easily dislodged so that the wearer should be alert and cooperative while the device is being worn to help keep the cannula in place. One means for alleviating the problem of dislodgement is described in U.S. Pat. No. 3,682,171 (Dali et al.--patented Aug. 8, 1972) wherein the cannula is kept in place by means of an arch-like nose bridge. The improvement described by Dali et al. minimizes one disadvantage of the nasal cannula, but does not minimize the other two.
Another delivery system employed is a nasal catheter which is a tube containing a number of gas delivery openings in one end which is inserted into the patient's nostril. While it possesses most of the advantages of the nasal cannula and is not dislodged as easily as the cannula, it is less comfortable than the nasal cannula, it can dry the nostrils and mucous membranes, it must be moved from one nostril to the other periodically and it may clog with secretions.
Another delivery system is the apparatus for delivering and permitting normal breathing of mixtures of gases taught in U.S. Pat. No. 2,241,535 (Boothby et al.--patented May 13, 1941). It is basically a mask covering the entire nose which is fed by two gas delivery tubes which encircle the wearer's mouth and lead to a rebreather bag, thereby permitting normal breathing of various concentrations of gases, particularly oxygen. The Boothby et al. apparatus is said to be capable of effectively and economically delivering up to 100 percent oxygen without having the wearer experience appreciable discomfort or irritation. It still possesses the disadvantage of having a bulky rebreather bag. The mask does not appear to be suitable for long-term usage due to its complexity and restrictions on movement caused by the tubes and bag hanging down in front of the wearer. Furthermore, the nose is entirely enclosed by the mask and thereby offers some resistance to normal breathing and can also result in moisture condensing on the bottom of the mask.
A simple, inexpensive nose mask which contains a single gas delivery tube having a single opening which positioned such that the entering gas stream does not directly flow against the face is taught in U.S. Pat. No. 2,859,748 (Hudson--patented Nov. 11, 1958). While it has many advantages, it still covers the entire nose thereby presenting some resistance to exhalation through the nose and could become uncomfortably warm and/or become wet as a result of water vapor (from the patient's breath or from water vapor added to the oxygen) condensing on the inside surface of the mask.
U.S. Pat. No. 2,174,523 (Manson--patented Oct. 3, 1939) teaches a face mask for airplane pilots which is said to permit normal unrestricted breathing and exhalation through the nose with ample provision for vocal communication. The nose is covered from the bridge to the lower edge by the mask. An oxygen distributor composed of two hollow tubes with a number of gas delivery openings is placed directly under the nose and in front of the mouth so that oxygen being supplied is directed at the nose and mouth of the wearer by a baffle plate to permit normal unrestricted breathing. Fogging of the pilot's goggles and formation of ice around the oxygen distribution tubes due to restricted exhalation is said to be avoided in this device because of the provision for unrestricted exhalation (around the sides). It does have the disadvantage of preventing one from eating since the mouth is covered. Furthermore, the mask covers a good portion of the wearer's face and would tend to be warm and uncomfortable over a long period of use.
Czechoslovakian Patent Specification No. 80,647 (Eng. Karel Urban--protected from Aug. 15, 1950) describes an air curtain which is basically a tube containing a downwardly-disposed single row of openings mounted on the edge of a holder resembling an eyeglass frame. The tube is held at about the level of the lower edge of the nose to provide an air curtain across the face to protect a worker such as a painter from vapors and airborne particles while providing him with a continuous supply of clean and fresh air. However, the configuration taught appears to require a large gas flow to be effective for its stated purpose which is an "air-curtain" barrier and does not appear to be designed for use in efficiently and economically administering gases to a human being.
A further summary of state of the art relating to oxygen delivery devices can be found on pages 104 to 107 of "Nursing Photobook.TM., Providing Respiratory Care," Robinson and Russo, editors, Intermed Communications, Inc., Horsham, Pa. 19044 (1979).
It thus appears that there is still a need for a device for efficiently administering at least one type of gas such as oxygen to a human being, especially for use on a long-term basis.